const generate = function (numRows) {
  let arr = [];
  for (let i = 0; i < numRows; i++) {
    let row = [];
    row[0] = 1;
    row[i] = 1;
    for (let j = 1; j < row.length - 1; j++) {
      row[j] = arr[i - 1][j - 1] + arr[i - 1][j];
    }
    arr.push(row);
  }
  return arr;
};

/**
 *  Author: Mcnwork2018
 */

var generate = function (numRows) {
  if (numRows === 0) return [];
  if (numRows === 1) return [[1]];
  if (numRows === 2) return [[1], [1, 1]];
  let triangleArray = [[1], [1, 1]];
  for (let i = 2; i < numRows; ++i) {
    triangleArray[i] = [];
    for (let j = 0; j < i + 1; ++j) {
      if (j === 0 || j === i) {
        triangleArray[i][j] = 1;
      } else {
        triangleArray[i][j] =
          triangleArray[i - 1][j - 1] + triangleArray[i - 1][j];
      }
    }
  }
  return triangleArray;
};
